We do have plans for a new developer site that has nightly tarball snapshots in the works.

Edit:
Forgot to mention there's also a new buildZCS.sh script. Throw in java & ant, use arguments like -t to build third party first (and -p will pick from a public perl location), then build zimbra in one sweep.
You can supply a -d argument to if you want to build a final instead of a dev build like the wiki takes you through.
(It is not required to build Third Party to build Desktop. However, you must have a licensed version of install4j.)